Cold Stress and Molecular Regulation of Gonadal Development in Crustaceans: Phenotypic Responses, Molecular Regulation, and Aquaculture Implications

Low temperature is a major environmental factor influencing the reproductive performance of crustaceans, particularly during gonadal development. This review synthesizes current knowledge on the phenotypic, physiological, and molecular responses of crustaceans to cold stress, with a focus on its regulatory effects on gonadal development. Available evidence indicates that low temperature generally delays gonadal maturation, reduces the gonadosomatic index, impairs oocyte development and yolk deposition, and suppresses spawning. Mechanistically, cold stress induces energy limitation and triggers a growth–reproduction trade-off, in which resources are preferentially allocated to survival and somatic maintenance rather than reproductive investment. This process is closely associated with lipid metabolism remodeling, mitochondrial dysfunction, and altered ATP-dependent energy sensing. At the molecular level, several pathways and regulatory factors are involved, including PI3K–Akt–FoxO, AMPK/mTOR, heat shock proteins, vitellogenin and its receptor, cell cycle regulators, antioxidant defense systems, and neuroendocrine mediators such as MIH, MOIH, and ecdysteroids. Emerging evidence also suggests potential roles for epigenetic regulation and species- or population-specific adaptation in shaping reproductive responses to low temperatures. Overall, this review provides an integrated framework for understanding how cold stress modulates crustacean gonadal development and highlights key directions for future studies and aquaculture applications. However, a comprehensive framework integrating energy metabolism, neuroendocrine signaling, and molecular pathways to explain reproductive suppression under cold stress is currently lacking.